Process for preparing beta-lactam antibiotic substances

ABSTRACT

Process for preparing β-lactam antibiotic substances useful as intermediate for various cephalosporin or penicillin derivatives, which comprises oxidation of 7-benzylideneaminocephem or 6-benzylideneaminopenam compounds capable of being converted to their quinoid forms by oxidation followed by reaction with lower alkanols.

This is a division of application Ser. No. 501,245, filed Aug. 28, 1974,now U.S. Pat. No. 4,016,155.

This invention relates to a new process for preparing β-lactamantibiotic substances. More particularly, it relates to a new processfor introducing an alkoxy group into a cephem nucleus at the 7-positionthereof or a penam nucleus at the 6-position thereof. Still moreparticularly, it is concerned with a new process for preparing aβ-lactam antibiotic substance which comprises oxidation of a7-benzylideneaminocephem compound or a 6-benzylideneaminopenam compound,both of which are capable of being converted to their quinoid forms byoxidation, followed by reaction with a lower alkanol to form a7β-benzylideneamino-7α-alkoxycephem compound or a6β-benzylideneamino-6α-alkoxypenam compound.

More specifically, this invention is concerned with a novel process forpreparing a compound having the formula ##STR1## R¹ to R⁶ areindividually groups which do not participate in the reaction, R is alower alkyl group, and n is an integer of 1 or 2 which comprisesoxidation of a compound having the formula ##STR2## wherein Z, R¹ to R⁵and n are as defined above and subsequent reaction with a lower alkanol.

For introducing an alkoxy group into a cephem nucleus at its 7-positionor into a penam nucleus at its 6-position, the following processes havebeen proposed in the art.

a. A process of diazotization of 7-aminocephalosporanic acid andsubsequent conversion into the corresponding alkoxy derivative (JapanesePatent Provisional Publication 931/1972; Journal of the AmericanChemical Society, Vol. 94, p. 1408 (1972)).

b. A process of alkylthiolation or fluorination and acylation of a 6- or7-benzylideneamino compound and subsequent conversion into thealkoxylated compound (Journal of Organic Chemistry, Vol. 38, p. 943 and2857 (1973)).

c. A process of reaction of a 7-benzylideneamino compound with a dialkylperoxy compound (Japanese Patent Provisional Publication 42691/1972).

d. A process wherein a 7-acylaminocephem compound or a 6-acylaminopenamcompound is subjected to N-chlorination and converted to thecorresponding acylimino compound (followed by) addition of methanol(Journal of the American Chemical Society, Vol. 95, p. 2401 and 2403(1973)).

However, the above-mentioned prior art processes have some drawbacks inthat, for instance, many reaction steps and complicated procedures arerequired with poor yields in the above process (a), and the processes(b) to (d) are industrially inadvantageous due to, e.g., lowertemperatures required.

As a result of our research on alkoxylation of a cephem nucleus at its7-position or a penam nucleus at its 6-position, we have found anddeveloped an improved and simple method which entirely differs from theprior methods and in which by-products are hardly formed and lowertemperatures are not required in the reaction procedures.

It is, accordingly, a primary object of this invention to provide a newand improved process for preparing β-lactam antibiotic substances whichis entirely different and unexpected from the prior art.

Other objects and advantages of this invention will become apparent fromthe following disclosure of this invention.

The compounds (I) which may be prepared by the process of this inventionare new substances not disclosed in the prior art and useful as anintermediate for the synthesis of various cephalosporin or penicillinderivatives each having a broad antibacterial spectrum.

For instance, the compounds obtained by the process of this inventioncan be reacted with an acylating agent directly or worked by existingsteps, for example, by the action of 2,4-dinitrophenyl hydrazine andp-toluenesulfonic acid to form an 7-amino-7-methoxycephalosporinderivative, which is then reacted with an acylating agent to form a7-methoxy-7-acylaminocephalosporin derivative followed by the removal ofthe protective group of the carboxylic acid at 4-position in aconventional manner, whereby a compound having a strong antibacterialactivity is produced.

In accordance with the present invention, there is provided, broadlyspeaking, a new process for preparing a β-lactam antibiotic substancewhich comprises oxidation of a 7-benzylideneaminocephem compound or a6-benzylideneaminopenam compound, both of which are capable of beingconverted to their quinoid forms, followed by reaction with a loweralkanol to form a 7β-benzylideneamino-7α-alkoxycephem compound or a6β-benzylideneamino-6α-alkoxypenam compound.

Specifically speaking, there is provided a new and advantageous processfor preparing a compound having the formula ##STR3## R¹ to R⁶ areindividually groups which do not participate in the reaction, R is alower alkyl group, and n is an integer of 1 or 2 which comprisesoxidation of a compound having the formula ##STR4## wherein Z, R¹ to R⁵and n are as defined above and subsequent reaction with a lower alkanol.

In one more specific aspect of this invention, there is provided aprocess for preparing a compound having the formula ##STR5## wherein R⁷represents hydrogen atom, methyl group, cyanomethyl group, anacyloxymethyl group, carbamoyloxymethyl group, an alkoxymethyl group, analkylthiomethyl group or a heterocyclic thiomethyl group, R⁸ representsa protective group for carboxyl group, R⁹ to R¹² may be the same ordifferent and each represents hydrogen atom, a straight or branchedlower alkyl group, an alkoxy group, a halogen atom, cyano group or analkoxycarbonyl group and R⁹ and R¹⁰ and R¹¹ and R¹² may form a ringfused with the benzene ring to which they are attached, n is 1 or 2 andR represents a lower alkyl group which comprises oxidation of a cephemcompound having the formula ##STR6## wherein R⁷ to R¹² and n have thesame meanings as defined above and subsequent reaction with a loweralkanol. In a preferred embodiment of this aspect, there is provided aprocess for preparing a compound having the formula ##STR7## wherein R⁷represents hydrogen atom, methyl group, cyanomethyl group, anacyloxymethyl group, carbamoyloxymethyl group, an alkoxymethyl group, analkylthiomethyl group or a heterocyclic thiomethyl group, R⁸ representsa protective group for carboxyl group, n is 1 or 2 and t-Bu istert.-butyl group which comprises oxidation of a compound having theformula ##STR8## wherein R⁷, R⁸, n and t-Bu have the same meanings asabove and subsequent reaction with methanol.

In another more specific aspect of this invention, there is provided aprocess for preparing a compound having the formula ##STR9## wherein R⁷represents hydrogen atom, methyl group, cyanomethyl group, anacyloxymethyl group, carbamoyloxymethyl group, an alkoxymethyl group, analkylthiomethyl group or a heterocyclic thiomethyl group, R⁸ representsa protective group for carboxyl group, R⁹ to R¹² may be the same ordifferent and each represents hydrogen atom, a straight or branchedlower alkyl group, an alkoxy group, a halogen atom, cyano group or analkoxycarbonyl group and R⁹ and R¹⁰ and R¹¹ and R¹² may form a ringfused with the benzene ring to which they are attached, n is 1 or 2 andR represents a lower alkyl group which comprises oxidation of a cephemcompound having the formula ##STR10## wherein R⁷ to R¹² and n have thesame meanings as defined above and subsequent reaction with a loweralkanol. In a preferred embodiment of this aspect, there is provided aprocess for preparing a compound having the formula ##STR11## wherein R⁷represents hydrogen atom, methyl group, cyanomethyl group, anacyloxymethyl group, carbamoyloxymethyl group, an alkoxymethyl group, analkylthiomethyl group or a heterocyclic thiomethyl group, R⁸ representsa protective group for carboxyl group, n is 1 or 2 and t-Bu istert.-butyl group which comprises oxidation of a compound having theformula ##STR12## wherein R⁷, R⁸, n and t-Bu have the same meanings asabove and subsequent reaction with methanol.

In another aspect of this invention, there is provided a process forpreparing a compound having the formula ##STR13## wherein R⁸ representsa protective group for carboxyl group, R⁹ to R¹² may be the same ordifferent and each represents hydrogen atom, a lower alkyl group, analkoxy group, a halogen atom, cyano group or an alkoxycarbonyl group andR⁹ and R¹⁰ and R¹¹ and R¹² may form a ring fused with the benzene ringto which they are attached, n is 1 or 2 and R represents a lower alkylgroup which comprises oxidation of a penam compound having the formula##STR14## wherein R⁸ to R¹² and n have the same meanings as definedabove and subsequent reaction with a lower alkanol. In a preferredembodiment of this aspect, there is provided a process for preparing acompound having the formula ##STR15## wherein R⁸ represents a protectivegroup for carboxyl group, n is 1 or 2 and t-Bu is tert.-butyl groupwhich comprises oxidation of a compound having the formula ##STR16##wherein R⁸, n and t-Bu have the same meanings as above and subsequentreaction with methanol.

With regard to the starting material (II) in the process of thisinvention, the 7-benzylideneaminocephem or 6-benzylideneaminopenamcompound capable of being converted to its quinoid form by oxidationmeans a Schiff base formed by a formyl compound of benzene or a fusedaromatic polycyclic hydrocarbon, e.g., naphthalene, anthracene orbiphenyl and an 7-aminocephem or 6-aminopenam compound, said benzene orhydrocarbon having hydroxy group at the conjugated position with theformyl group. As the examples of the aforesaid formyl compound arementioned p-hydroxybenzaldehyde, 4-formyl-1-naphthol,5-formyl-1-naphthol, 9-formyl-10-hydroxyanthracene, 4-(4-hydroxyphenyl)benzaldehyde and the like. On the benzene ring or fused benzene ring ofthe above groups may be optionally present any of those substituentsthat do not participate in the present reaction. Also, on the cephem orpenam nucleus may be present the substituents that do not participate inthe present reaction. The benzylideneamino group at 7- or 6-position ofthe cephem or penam nucleus, respectively, may be of α- orβ-configuration.

In the above formula, R¹ to R⁶ may be any of those groups that do notparticipate in the present reaction. As the examples of the group R⁶ arementioned the substituents taking the 3-position in previously knownnatural and synthetic cephem compounds, the representatives thereofbeing hydrogen atom, methyl group, cyanomethyl group, acyloxymethylgroups such as alkanoyloxymethyl, e.g., acetoxymethyl,propionyloxymethyl, pivaloyloxymethyl or aroyloxymethyl, e.g.,benzoyloxymethyl, carbamoyloxymethyl group, alkoxymethyl groups such asmethoxymethyl, ethoxymethyl, butyloxymethyl, alkylthiomethyl groups suchas methylthiomethyl, ethylthiomethyl, propylthiomethyl, heterocyclicthiomethyl groups such as 2-pyridylthiomethyl,2-(1,3,5-triazolo)thiomethyl, 3-pyrazolothiomethyl, 1imidazolinylthiomethyl, 5-methyl-1,3,4-thiadiazolyl-2-thiomethyl,1-methyl-1H-tetrazol-5-yl-thiomethyl. The group R¹ is a protective groupof the carboxyl group in carrying out the process of this invention,including those groups easily removable in subsequent step withoutdestruction of the cephem or penam nucleus and those groups that mayremain in the final product. As the examples of such protective groupare mentioned a straight or branched lower alkyl group such as methyl,ethyl, propyl, isopropyl, butyl, tert-butyl and substituted methylgroups such as lower alkoxy methyl or benzyloxymethyl groups, e.g.,methoxymethyl, ethoxymethyl, benzyloxymethyl, p-nitrobenzyloxymethyl;lower alkanoyloxy lower alkyl groups, e.g., acetoxymethyl,pivaloyloxymethyl, 1-acetoxyethyl, 1-acetoxypropyl, 1-pivaloyloxyethyl;benzoyloxymethyl group; cyanomethyl group; 2,2,2-trichloroethyl group;phthalimidomethyl group; benzyl groups such as benzyl, p-methoxybenzyl,p-nitrobenzyl; benzhydryl group; phenacyl groups such as phenacyl,p-bromophenacyl, p-methoxyphenacyl, p-nitrophenacyl and tri lower alkylsilyl groups such as trimethylsilyl and the like. The groups R² to R⁵may be any of those groups that would not adversely affect the compoundhaving the above-mentioned formula (II) to take its quinoid form. As theexamples of such group are mentioned, for instance, hydrogen atom;straight or branched lower alkyl groups such as methyl, ethyl, propyl,isopropyl, tert.-butyl; lower alkoxy groups such as methoxy, ethoxy,propoxy, isopropoxy,tert.-butoxy; halogen atoms such as chlorine,bromine; cyano group; lower alkoxycarbonyl groups such asmethoxycarbonyl, ethoxycarbonyl,tert.-butoxycarbonyl and the like. R²and R³ or R⁴ and R⁵ may be linked together to form a ring fused with thebenzene ring to which they are attached. n is 1 or 2 and, when n is 2,for example biphenyl, binaphthalene, p-(4 -naphthyl)benzene may beformed. Usually, a phenyl group having a sterically hindered alkylgroup, e.g., tert.-butyl at orthoposition to the hydroxy group may besuitable used.

As the oxidizing agents which may be employed in the process of thisinvention may be effectively used any of those agents that could oxidizephenol to a quinoid form without destruction of the cephem or penamnucleus and as the examples of such agents are preferably mentionedmetal oxides such as lead dioxide, manganese dioxide and the like;quinone compounds such as benzoquinones having as substituents electronattractive groups, e.g., dichlorodicyanobenzoquinone, chloranil and thelike and lead dioxide and dichlorodicyanobenzoquinone are particularlyadvantageous in view of its easy availability and inexpensiveness andits reactivity.

The lower alkoxy group to be introduced in this invention may bestraight or branched and, thus, as the lower alkanol which may beemployed in the process of this invention are preferably of 1 to 6carbon atoms and exemplified by straight or branched lower alkanols suchas methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol,sec.-butanol, tert.-butanol, n-pentanol, n-hexanol.

The process of this invention consists of a oxidation step and asubsequent alkoxylation step.

In practising the present process, the oxidation step is conducted bybringing the compound having the above-mentioned formula (II) intocontact with an oxidizing agent in a suitable solvent. The solvent whichmay be employed in the reaction is of no particular limitation if itwill not participate with the reaction and various inert organicsolvents may be mentioned. As examples of such solvents may bementioned, for instance, aromatic hydrocarbons such as benzene, toluene,halogenated hydrocarbons such as chloroform, methylene chloride; etherssuch as dioxane, tetrahydrofuran and the like. The aromatic hydrocarbonssuch as benzene may be usually employed. The reaction may proceed withan oxidizing agent in a stoichiometric amount, but it is usuallypreferred for effecting rapid reaction to use an excess amount (about1.5 - 10 times moles) of the oxidizing agent. The reaction temperatureis not particularly critical, but the reaction may be usually effectedat a temperature from room temperature to about 80° C. However, it is tobe noted that the reaction may proceed at higher or lower temperatures.The time required for the reaction may be varied mainly upon thestarting compound, the kind of the oxidizing agent, the sort of thesolvent, the reaction temperature and the like, but it may usually takeabout 10 minutes to several hours. The compound having theabove-mentioned formula (II) which may be employed in the process ofthis invention may be formed in situ by the interaction of an7-aminocephalosporin or 6-aminopenicillin compound with an aryl aldehydeprior to the practice of the process of this invention and used per sein the present reaction.

The product formed by the oxidation may be recovered in a usual manner.For instance, the oxidizing agent is filtered off from the reactionmixture and the solvent is distilled off from the filtrate under reducedpressure to give the product. This product may be purified by aconventional method, e.g., column chromatography, but the product per semay be preferably employed without isolation and purification as astarting compound in the form of a solution in the subsequent stepaccording to the process of this invention.

The alkoxylation step may be easily effected by contacting a solution ofthe aforesaid starting compound with a lower alkanol. The reaction mayproceed in a stoichiometric amount of the alkanol, but an excess amountof the lower alkanol of about 10 - 100 times moles may be usually andpreferably used for rapid reaction. The reaction temperature is notparticularly critical and the reaction may be usually conducted at roomtemperature, but the reaction may proceed at higher or lowertemperatures. As the reaction may be promoted with heating, the reactionmay be, in some cases, effected with heating to about 40°-50° C. Thetime required for the reaction may be varied mainly upon the kind of thestarting compound, the sort of the lower alkanol, the reactiontemperature and the like, but it takes about 0.5- several hours.

The alkoxylated compound may be recovered from the reaction mixture in ausual manner. For instance, the solvent and excess alkanol are distilledoff from the reaction mixture to give the amorphous end product in thisstep, which may be then purified by a conventional method, e.g., columnchromatography.

The process of this invention may be more concretely illustrated by wayof the examples and referential examples given below, but this inventionis not to be limited by them.

EXAMPLE 1 2,2,2-Trichloroethyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylateStep A 2,2,2-Trichloroethyl 7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylate

To 10 g. of 2,2,2-trichloroethyl7β-amino-3-methyl-3-cephem-4-carboxylate hydrochloride was added about70 ml. of water. About 2.5 g. of sodium bicarbonate was added theretoand, after stirring for a while, the resultant was extracted with ethylacetate. The extract was dried over anhydrous sodium sulfate andconcentrated at a temperature below 35° C. The so obtained free base wasdissolved in 40 ml. of methanol and 5 g. of4-hydroxy-3,5-di-tert.-butylbenzaldehyde was added thereto and stirringwas continued at room temperature for 4 hours. The insolubles weredissolved by heating briefly and the reaction mixture was concentratedinto a half amount thereof, which was then cooled to separate outcrystalline substances. The substances were recovered by filtration andwashed with cold methanol to give 2,2,2-trichloroethyl7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylate.Yield 7 g. The product was recrystallized from a small amount ofmethanol to give the pure product as slightly yellow colored crystals.m.p. 94° C.

Analysis for C₂₅ H₃₁ O₄ N₂ SCl₃ : Calculated: C, 53.43; H, 5.56; N,4.99; Found: C, 53.51; H, 5.61; N, 5.08

Step B 2,2,2-Trichloroethyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylate

A mixture of 1 g. of 2,2,2-trichloroethyl7β-(4-hydroxy-3,5-di-tert.-butyl-benzylideneamino)-3-methyl-3-cephem-4-carboxylateand 5 g. of lead dioxide in 75 ml. of benzene was refluxed with stirringfor 15-20 minutes. After cooling, insolubles were filtered off andwashed with benzene. The combined filtrate and washings wereconcentrated under reduced pressure to about 20 ml. and about 10 ml. ofabsolute methanol was added to the residue. After standing for 1 hour atroom temperature, the reaction mixture was concentrated under reducedpressure to give the desired product. The product was purified by acolumn chromatography on dried silica gel (dried at 110° C. underreduced pressure for several hours) and elution with a solution systemof cyclohexane-ethylacetate (3 : 1) to give 2,2,2-trichloroethyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylateas pale brown amorphous powders.

Yield 700 mg.

The product has M⁺ 590 in its mass spectrum.

Nmr spectrum (CDCl₃) δ ppm:

1.45 (C·(CH₃)₃, singlet),

2.21 (CH₃ at 3-position, singlet),

3.35 (H₂ at 2-position, quartet),

3.60 (OCH₃ at 7-position, singlet),

4.90 (CO₂ CH₂ CCl₃, quartet),

5.06 (H at 6-position, singlet),

5.55 (OH at 4-position of benzene OH, singlet),

7.65 (benzene H, singlet),

8.55 (CH═N--, singlet),

Tlc (thin-layer chromatography) (silica gel):

Developing solvent, cyclohexane - ether (2 : 1)

R_(f) = 0.5

EXAMPLE 2 Benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butyl-benzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

A mixture of 880 mg. of benzhydryl 7-aminocephalosporanate and 460 mg.of 4-hydroxy-3,5-di-tert.-butyl-benzaldehyde was refluxed in 50 ml. ofbenzene for 1.5 to 2 hours by the removal of water using a waterseparator to form the Schiff base in situ, which was used in subsequentreaction without any isolation procedures. To the reaction mixture wasadded 5 g. of lead dioxide and vigorous stirring was done for 15 minutesin an oil bath at 85° C. After cooling, the reaction mixture wasfiltered and 20 ml. of absolute methanol was added to the filtrate.After standing for 1 hour at room temperature, the reaction mixture wasconcentrated under reduced pressure to give a crude product. The productwas purified by elution with a mixture of cyclohexane-ethyl acetate (3: 1) on a column using about 50 g. of silica gel which was dried byheating under reduced pressure, thereby giving benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate.Yield 0.9 g.

Nmr spectrum (CDCl₃) δ ppm:

1.45 (C·(CH₃)₃, singlet),

1.98 (CH₂ OCOCH₃ at 3-position, singlet),

3.35 (H₂ at 2-position, quartet),

3.55 (OCH₃ at 7-position OCH₃, singlet),

4.80 (CH₂ OCOCH₃ at 3-position, quartet),

5.03 (H at 6-position, singlet),

5.50 (OH at 4-position of benzene, singlet),

6.07 (COOCH(C₆ H₅)₂, singlet),

7.30 (COOCH (C₆ H₅)₂, singlet),

7.63 (H at 2,6-positions of benzene, singlet),

8.45 (CH ═ N--, singlet),

TLC (silica gel):

Developing solvent, n-hexane-ethyl acetate (3 : 1)

R_(f) = 0.4

EXAMPLE 3 Benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-(1-methyl-1H-tetrazol-5-yl)thiomethyl-3-cephem-4-carboxylate

To 70 ml. of benzene were added 7.0 g of benzhydryl7-amino-3-(1-methyl-1H-tetrazol-5-yl)-thiomethyl-3-cephem-4-carboxylateand 3.5 g. of 4-hydroxy-3,5-di-tert.-butylbenzaldehyde. The mixture wasrefluxed for 1.5 hours, while the water formed in situ during thereaction was removed by the use of a water separator. The resultingSchiff base solution was added to a mixture of 50 g. of lead dioxide and300 ml. of benzene, which was pre-heated to 65° C under stirring. Theresulting mixture was vigorously stirred at 65° C for 15 minutes. Aftercooling, the reaction mixture was filtered and to the filtrate was added50 ml. of absolute methanol. The mixture was left standing at roomtemperature and then concentrated under reduced pressure to give thecrude desired product. This product was purified by a columnchromatography on dried silica gel, using a developing solvent ofbenzene-ethyl acetate (10 : 1) to give 4.65 g. of benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-(1-methyl-1H-tetrazol-5-yl)thiomethyl-3-cephem-4-carboxylateas pale reddish brown colored amorphous powders.

Nmr spectrum (CDCl₃) δ ppm:

1.45 (C·(CH₃)₃, singlet),

3.58 (OCH₃ at 7-position, singlet),

3.61 (H₂ at 2-position, singlet),

3.79 (N--CH₃ in tetrazole at 3-position, singlet),

4.31 (--CH₂ S-- at 3-position, quartet),

5.09 (H at 6-position, singlet),

5.63 (OH at 4-position in benzene, singlet),

6.98 (COOCH (C₆ H₅)₂, singlet),

7.38 (COOCH (C₆ H₅)₂, singlet),

7.72 (H at 2,6-positions in benzene, singlet),

8.60 (--CH═N--, singlet)

Tlc (silica gel):

Developing solvent, benzene-ethyl acetate (10 : 1)

R_(f) = 0.4

Following the substantially same procedures as above except that thereaction of the Schiff have and the lead dioxide was effected at atemperature of about 5°-10° C. under icecooling, there was obtained asimilar result.

EXAMPLE 4 Benzhydryl7α-methoxy-7β-(4-hydroxy-3-methyl-5-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

A mixture of 438 mg. of benzhydryl 7-aminocephalosporanate and 192 mg.of 4-hydroxy-3-methyl-5-tert-butylbenzaldehyde was refluxed for 1.5hours in 15 ml. of benzene, while water is removed by a water separatorto form the corresponding Schiff base. The reaction mixture was cooledand 1 g. of lead dioxide was added thereto. The mixture was vigorouslystirred at room temperature for 30 minutes. The mixture was filtered andto the filtrate was added 4 ml. of absolute methanol and the solutionwas left standing at room temperature for 18 hours. The reaction mixturewas concentrated under reduced pressure and the residue was purified bya column chromatography on silica gel, which was previously dried byheating under reduced pressure, by the use of a mixture of cyclohexaneand ethyl acetate(3 : 1) as a developing solvent to give benzhydryl7α-methoxy-7β-(4-hydroxy-3-methyl-5-tert-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateas pale yellow colored amorphous powders.

Yield 120 mg.

Nmr spectrum (CDCl₃) δ ppm:

1.42 (C· (CH₃)₃, singlet),

1.98 (CH₂ COOCH₃ at 3-position, singlet),

2.23 (CH₃ at 3-position in benzene, singlet),

3.39 (H₂ at 2-position, quartet),

3.58 (OCH₃ at 7-position, singlet),

4.85 (CH₂ OCOCH₃ at 3-position, quartet),

5.07 (H at 6-position, singlet),

5.50 (OH at 4-position in benzene, singlet),

6.98 (COOCH (C₆ H₅)₂, singlet),

7.37 (COOCH (C₆ H₅)₂, singlet),

7.59 (H at 2,6-positions in benzene, singlet),

8.53 (CH═N--, singlet),

Tlc (silica gel):

Developing solvent, cyclohexane-ethyl acetate (3 : 1)

R_(f) = 0.40

EXAMPLE 5 Benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-dimethylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateStep A Benzhydryl7β-(4-hydroxy-3,5-dimethylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

A mixture of 658 mg. of benzhydryl 7-aminocephalosporanate and 225 mg.of 4-hydroxy-3,5-dimethylbenzaldehyde were refluxed in 25 ml. of toluenefor 2 hours, while water is removed by a water separator. After cooling,benzhydryl7β-(4-hydroxy-3,5-dimethylbenzylideneamino)-3-acetoxymethyl-4-cephem-4-carboxylatewas separated out in situ as colorless crystals, which were thenrecovered by filtration and washed with a small amount of toluene. Yield690 mg. m.p. 187°-188° C (with decomp.)

Step B Benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-dimethylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

In 20 ml. of hot benzene was dissolved 300 mg. of benzhydryl7β-(4-hydroxy-3,5-dimethylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateand 0.9 g of lead dioxide was added thereto. The mixture was stirred atroom temperature for 30 minutes. The reaction mixture was filtered, tothe filtrate was added 3 ml. of methanol and the mixture was left atroom temperature for 18 hours. The reaction mixture was concentratedunder reduced pressure. The residue was purified by a columnchromatography using a mixture of cyclohexane and ethyl acetate (2 : 1)and silica gel, which was previously dried by heating under reducedpressure. By this purification was obtained benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-dimethylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateas pale yellow powders.

Yield 10 mg.

Nmr spectrum (CDCl₃) δ ppm:

1.98 (OCOCH₃ at 3-position, singlet),

2.25 (CH₃ at 3,5-positions in benzene, singlet),

3.38 (H₂ at 2-position, quartet),

3.56 (OCH₃ at 7-position, singlet),

4.93 (CH₂ OCOCH₃ at 3-position, quartet),

5,06 (H at 6-position, singlet),

6.98 (COOCH (C₆ H₅)₂, singlet),

7.35 (COOCH (C₆ H₅)₂, singlet),

7.50 (H at 2,6-positions, singlet),

8.48 (CH═N--, singlet)

Tlc (silica gel):

Developing solvent, cyclohexane-ethyl acetate (2 : 1)

R_(f) = 0.4

EXAMPLE 6 benzhydryl7α-ethoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

In 50 ml. of benzene was dissolved 2 g. of benzhydryl3-acetoxymethyl-7-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-cephem-4-carboxylateand 5 g. of lead dioxide was added thereto. Heating with stirring wasdone for 15 minutes. After cooling the reaction mixture was filtered andto the filtrate was added 20 ml. of ethanol. The resulting mixture wasleft at room temperature for 1.5 hours. The reaction mixture wasconcentrated at room temperature and the residue was purified by acolumn chromatography on dried silica gel, using a developing solvent ofcyclohexane and ethyl acetate (3 : 1) to give 700 mg. of benzyhydryl7α-ethoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateas reddish orange colored powders.

Nmr spectrum (CDCl₃) δ ppm:

1.22 (OCH₂ CH₃ at 7-position, triplet), 1,45 (C.sup.. (CH₃)₃, singlet),

2.00 (CH₂ OCOCH₃ at 3-position, singlet),

3.41 (H₂ at 2-position, doublet),

3.83 (OCH₂ CH₃ at 7-position, quartet),

4.90 (--CH₂ OAc at 3-position, quartet),

5.05 (H at 6-position, singlet),

5.62 (phenolic OH, singlet),

6.98 (COOCH (C₆ H₅)₂, singlet),

7.38 (COOCH (C₆ H₅)₂, singlet),

7.72 (H at 2,6-positions in benzene nucleus, singlet),

8.56 (C═N--, singlet).

EXAMPLE 7 Benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-diisopropylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

In 15 ml. of benzene was dissolved 500 mg. ofbenzhydryl-7-(4-hydroxy-3,5-diispropylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylteand 1 g. of PbO₂ (lead dioxide) which was freshly prepared, was addedthereto. The resulting mixture was stirred at room temperature for 20minutes. Insolubles were filtered off, to the filtrate was added 4 ml.of methanol and then the mixture was left at room temperature overnight.The reaction mixture was concentrated under reduced pressure to give thedesired product. The product was purified by a column chromatography ondried silica gel (dried at 110° C. under reduced pressure for severalhours), using as a developing solvent a mixture of cyclohexane-ethylacetate (3 : 1) to give benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-diisopropylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateas pale yellow colored amorphous powders.

Yield 202 mg.

Nmr spectrum (CDCl₃) δ ppm:

1.30 (CH.sup.. (CH₃)₂, doublet),

2.00 (CH₂ OCOCH₃ at 3-position, singlet),

3.14 (CH (CH₃)₂, multiplet),

3.42 (H₂ at 2-position, quartet),

3.61 (OCH₃ at 7-position, singlet),

4.88 (CH₂ OCOCH₃ at 3-position, quartet),

5.13 (H at 6-position, singlet),

7.03 (COOCH (C₆ H₅)₂, singlet),

7.41 (COOCH (C₆ H₅)₂, singlet),

7.61 (H at 2,6-positions of benzene, singlet), 8.60 (CH═N--, singlet)

Tlc (silica gel):

Developing solvent, cyclohexane-ethyl acetate (3 : 1)

R_(f) = 0.3

EXAMPLE 8 Benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-(2-(5-methyl-1,3,4-thiadiazolyl)-thiomethyl)-3-cephem-4-carboxylate

In 10 ml. of benzene was dissolved 300 mg. of benzhydryl7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-(2-(5-methyl-1,3,4-thiadiazolyl)thiomethyl)-3-cephem-4-carboxylateand 600 mg. of lead dioxide was added thereto. The mixture was stirredat room temperature for 30 minutes. The reaction mixture was filteredand to the filtrate was added 4 ml. of methanol followed by standing atroom temperature for 1 hour. The reaction mixture was concentrated andthe residue was purified by a column chromatography on dried silica gel,using a developing solvent of cyclohexane-ethyl acetate (2 : 1) to give180 mg. of benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-(2-(5-methyl-1,3,4-thiadiazolyl)-thiomethyl)-3-cephem-4-carboxylateas pale yellow colored powders.

Nmr spectrum (CDCl₃) δ ppm:

1.44 (C.sup.. (CH₃)₃, singlet),

2.66 (CH₃ at 5-position in thiadiazole on 3-position, singlet),

3.57 (H₂ at 2-position and OCH₃ at 7-position, singlet),

4.32 (--CH₂ S-- at 3-position, quartet),

5.06 (H at 6-position, singlet),

5.60 (phenolic OH, singlet),

6.95 (COOCH (C₆ H₅)₂, singlet),

7.33 (COOCH (C₆ H₅)₂, singlet),

7.66 (H at 2,6-positions of benzene nucleus, singlet),

8.53 (CH ═ N--, singlet).

Tlc (silica gel):

Developing solvent, cyclohexane-ethyl acetate (2 : 1)

R_(f) = 0.4

EXAMPLE 9 p-Toluenesulfonylethyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylate

In 40 ml. of benzene was dissolved 1.0 g. of p-toluenesulfonylethyl7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylateand 2 g. of lead dioxide was added thereto. The mixture was stirred atroom temperature for 30 minutes. The reaction mixture was filtered, thefiltrate was concentrated under reduced pressure to a half amountthereof, 20 ml. of methanol was added thereto and the mixture was leftat room temperature overnight. The reaction mixture was concentrated andthe residue was purified by a column chromatography on dried silica gel,using eluants of cyclohexane-ethyl acetate (10 : 1 and 5 : 1) to give0.45 g. of p-toluenesulfonylethyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylateas powders.

Nmr spectrum (CDCl₃) δ ppm:

1.41 (C.sup.. (CH₃)₃, singlet),

2.00 (CH₃ at 3-position, singlet),

2.40 (C₆ H₄.sup.. CH₃ in ester, singlet),

3.21 (H₂ at 2-position, quartet),

3.53 (COOCH₂ CH₂ SO₂ in ester, triplet),

3.54 (OCH₃ at 7-position, singlet),

4.55 (COOCH₂ CH₂ SO₂ in ester, triplet),

4.96 (H at 6-position, singlet),

5.59 (phenolic OH, singlet),

7.59 (SO₂ --C₆ H₄ --CH₃ in ester, quartet),

7.63 (H at 2,6-positions in benzene nucleus, singlet),

8.44 (CH ═ N--, singlet)

Tlc (silica gel):

Developing solvent, cyclohexane-ethyl acetate (5: 1)

R_(f) = 0.5

EXAMPLE 10 Benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

To 350 mg. of benzhydryl7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylatewas added a solution of 113.5 mg. of2,3-dichloro-5,6-dicyanobenzoquinone in 8.6 ml. of benzene and theresulting mixture was stirred at room temperature for 30 minutes. Thereaction mixture was concentrated and the residue was extracted with amixture of cyclohexane-ethyl acetate (5 : 1). The extract wasconcentrated, the concentrate was again disolved in 5 ml. of benzene, 4ml. of methanol was added thereto and the mixture was left standing atroom temperature for 30 minutes. Then, the reaction mixture wasconcentrated under reduced pressure to give the crude product. Thisproduct was purified by a dry silica gel column chromatography elutingwith cyclohxane-ethyl acetate (3 : 1) to give benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate.Yield 156 mg.

The NMR spectrum and thin-layer chromatography of this product coincidedwith those shown in Example 2.

EXAMPLE 11 Benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

In 8.6 ml. of methanol were dissolved 330 mg. of benzhydryl7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateand 113.5 mg. of 2,3-dichloro-5,6-dicyanobenzoquinone and the resultingsolution was stirred in an ice bath for 10 minutes. The reaction mixturewas concentrated and the concentrate was extracted with benzene. Thebenzene extract was concentrated and the residue was chromatographed ona dry silica gel column with cyclohexane-ethyl acetate (3 : 1) as eluantto give benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateas amorphous powders.

Yield 161 mg.

The NMR spectrum and thin-layer chromatography of this product coincidedwith those shown in Example 2.

EXAMPLE 12 2,2,2-Trichloroethyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylate

In 7.6 ml. of methanol were dissolved 281 mg. of the7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamine)-3-methyl-3-cephem-4-carboxylateobtained in step A of Example 1 and 113.5 mg. of2,3-dichloro-5,6-dicyanobenzoquinone and the resulting solution wasstirred in an ice bath for 10 minutes. The reaction mixture wasconcentrated and the concentrate was extracted with benzene. The benzeneextract was concentrated and the residue was chromatographed on a drysilicon gel column with cyclohexane-ethyl acetate (3 : 1) to give2,2,2-trichloroethyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-methyl-3-cephem-4-carboxylateas amorphous powders. Yield 162 mg.

The NMR spectrum and thin-layer chromatography of this product coincidedwith those shown in step B of Example 1.

EXAMPLE 13 Benzhydryl7α-methoxy-7β-(4-hydroxy-3-tert.-butyl-1-naphthylmethyleneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

In 25 ml. of benzene was dissolved 1.0 g. of benzhydryl7β-(4-hydroxy-3-tert.-butyl-1-naphthylmethyleneamino)-3-acetoxymethyl-3-cephem-4-carboxylate,2 g. of lead dioxide was added thereto with stirring in an ice-waterbath and the mixture was stirred for 20 minutes in an ice-water bath.Insolubles were filtered off, 10 ml. of methanol was added to thefiltrate, and, after standing at room temperature overnight, thereaction mixture was concentrated under reduced pressure to give thedesired product. The product was purified by a column chromatography ondry silica gel developed with benzene - ethyl acetate (10 : 1) to givebenzhydryl7α-methoxy-7β-(4-hydroxy-3-tert.-butyl-1-naphthylmethyleneamino)-3-acetoxymethyl-3-cephem-4-carboxylateas powders. Yield 536 mg.

Nmr spectrum (CDCl₃) δ ppm:

1.43 (C·(CH₃)₃, singlet),

1.93 (CH₂ OCCCH₃ at 3-position, singlet),

3.32 (H₂ at 2-position, quartet),

3.56 (OCH₃ at 7-position, singlet),

5.06 (H at 6-position, singlet),

6.93 (COOCH(C₆ H₅)₂, singlet),

7.28 (COOCH (C₆ H₅)₂, multiplet)

Tlc (silica gel):

Developing solvent, benzene-ethyl acetate (10 : 1)

R_(f) = 0.4

EXAMPLE 14 Benzhydryl7α-methoxy-7β-(4-hydroxy-3-tert.-butyl-5,6,7,8-tetrahydro-1-naphthylmethyleneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

In 10 ml. of 1,2-dichloroethane was dissolved 260 mg. of benzhydryl7β-(4-hydroxy-3-tert.-butyl-5,6,7,8-tetrahydro-1-naphthylmethyleneamino)-3-acetoxymethyl-3-cephem-4-carboxylate,520 mg. of load dioxide was added thereto with stirring in an ice-waterbath and the mixture was stirred for 20 minutes in an ice-water bath.Insolubles were filtered off, 5 ml. of methanol was added to thefiltrate and, after standing at room temperature for 1.5 hours, thereaction mixture was concentrated under reduced pressure to give thedesired product. The product was purified by a column chromatography ondried silica gel developed with benzene - ethyl acetate (30 : 1) to givebenzhydryl7α-methoxy-7β-(4-hydroxy-3-tert.-butyl-5,6,7,8-tetrahydro-1-naphthylmethyleneamino)-3-acetoxymethyl-3-cephem-4-carboxylateas powders. Yield 155 mg.

Nmr spectrum (CDCl₃) δ ppm:

1.33 (C·(CH₃)₃, singlet),

1.70 (H₂ at 6,7-positions in 5,6,7,8-tetrahydronaphthylmethylenenucleus, broad singlet),

1.90 (CH₂ COOCH₃ at 3-position, singlet),

2.70 (H₂ at 5,8-positions in 5,6,7,8-tetrahydronaphthylmethylenenucleus, broad doublet),

3.40 (H₂ at 2-position, quartet),

3.48 (CCH₃ at 7-position, singlet),

4.79 (CH₂ OCOCH₃ at 3-position, quartet),

4.96 (H at 6-position, singlet),

6.84 (COOCH (C₆ H₅)₂, singlet),

7.23 (COOCH (C₆ H₅)₂, broad singlet),

7.67 (H at 2-position in 5,6,7,8-tetrahydronaphthylmethylene nucleus,singlet).

8.70 (CH:N--, singlet)

Tlc (silica gel):

Developing solvent, benzene-ethyl acetate (10 : 1)

R_(f) = 0.5

EXAMPLE 15 p-Bromophenacyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylate

In 30 ml. of 1,2-dichloroethane was dissolved 1.0 g. of p-bromophenacyl7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateand 2.0 g. of lead dioxide was added thereto when an inner temperaturereached -5° C. with stirring in an ice-salt bath. Then, the mixture wasstirred, maintaining the temperature at 0° - - 5° C. for 30 minutes.Insolubles were filtered off, 10 ml. of methanol was added to thefiltrate and the mixture was left at room temperature overnight. Thereaction mixture was concentrated under reduced pressure to give thedesired product. The compound was purified by a column chromatography ondried silica gel developed with benzene - ethyl acetate (10 : 1) to givep-bromophenacyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateas powders.

Yield 628 mg.

Nmr spectrum (CDCl₃) δ ppm:

1.46 (C·(CH₃)₃, singlet),

2.06 (CH₂ COOCH₃ at 3-position, singlet),

3.43 (H₂ at 2-position, quartet),

3.54 (OCH₃ at 7-position, singlet),

4.99 (CH₂ OCOCH₃ at 3-position, broad singlet),

5.08 (H at 6-position, singlet),

5.49 (COOCH₂ COC₆ H₄ Br, quartet),

5.61 (phenolic OH, singlet),

7.67 (H at 2,6-positions in benzene nucleus, singlet),

7.72 (COOCH₂ CO C₆ H₄ Br, quartet),

8.52 (CH═N--, singlet)

Tlc (silica gel):

Developing solvent, benzene-ethyl acetate (10 : 1)

R_(f) = 0.5

EXAMPLE 16 p-Bromophenacyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-(1-methyl-1H-tetrazol-5-yl)-thiomethyl-3-cephem-4-carboxylate

In 20 ml. of tetrahydrofuran was dissolved 724 mg. of p-bromophenacyl7β-(4-hydroxy-3,5-di-tert.-butylbenzylidenamino)-3-(1-methyl-1H-tetrazol-5-yl)thiomethyl-3-cephem-4-carboxylate,1.6 g. of lead dioxide was added thereto with stirring in an ice-waterbath and the mixture was stirred for 30 minutes in an ice-water bath.Insolubles were filtered off, 10 ml. of methanol was added to thefiltrate and, after standing at room temperature for 1 hour, thereaction mixture was concentrated under reduced pressure to give thedesired product. The product was purified by a column chromatography ondried silica gel developed with benzene - ethyl acetate (10 : 1) to givep-bromophenacyl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-(1-methyl-1H-tetrazol-5-yl)-thiomethyl-3-cephem-4-carboxylateas pale yellow powders. Yield 512 mg.

Nmr spectrum (CDCl₃) δ ppm:

1.39 (C·(CH₃)₃, singlet),

3.48 (OCH₃ at 7-position, singlet),

3.61 (H₂ at 2-position, singlet),

3.81 (N-CH₃ in tetrazole at 3-position, singlet),

4.38 (--CH₂ S-- at 3 -position, singlet),

5.03 (H at 6-position, singlet),

5.45 (COOCH₂ COC₆ H₄ Br, singlet),

5.55 (phenolic OH, singlet),

7.61 (H at 2,6-positions in benzene nucleus, singlet),

7.66 (COOCH₂ COC₆ H₄ Br, quartet),

8.46 (--CH═N--, singlet)

Tlc (silica gel):

Developing solvent, benzene-ethyl acetate

(10 : 1)

R_(f) = 0.3

EXAMPLE 17 2,2,2-Trichloroethyl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-6α-methoxypenicillanate

To 1.89 g. of 2,2,2-trichloroethyl6-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-penicillanate in 40 ml.of benzene was added 3.8 g. of lead dioxide. After stirring at roomtemperature for 20 minutes, insolubles were filtered off, and then thefiltrate was concentrated at room temperature to about one-half of itsoriginal volume. To this concentrate was added 15 ml. of methanol, and,after standing at room temperature for one hour, the solvent wasdistilled off. The residue thus obtained was purified by a dry silicagel column chromatography (3 × 36 cm, eluent; ethyl acetate -cyclohexane, 1 : 10) to give 725 mg. of 2,2,2-trichloroethyl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-6α-methoxypenicillanateas a pale yellow powder.

Ir spectrum ν_(max) ^(nujol) cm⁻¹ : 3650, 1770, 1690, 1635

Nmr spectrum δ ppm (CDCl₃)

8.47 (1H, singlet, 6-position CH═N)

7.66 (2h, singlet, benzene ring H)

5.59 (1h, singlet, 5-position H)

4.78 (2h, singlet, CH₂ CCl₃)

4.55 (1H, singlet, 3-position H)

3.55 (3h, singlet, 6-position OCH₃)

1.66 (3h, singlet, 2-position CH₃)

1.53 (3h, singlet, 2-position CH₃)

1.43 (18h, singlet, t-butyl)

EXAMPLE 18 Pivalcyloxymethyl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-6α-methoxypenicillanate

Following the same procedure as described in Example 17, there wasobtained 750 mg. of pivaloyloxymethyl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-6α-methoxypenicillanatefrom 1.89 g. of pivaloyloxymethyl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-penicillanate.

Ir spectrum ν_(max) ^(CHCl).sbsp.3 cm⁻¹ : 3630, 1760, 1630

Nme spectrum δ ppm (CDCl₃)

8.45 (1H, singlet, 6-position CH═N)

7.64 (2h, singlet, benzene ring H) 5.84 (2H, singlet, COOCH₂ O--)

5.58 (1h, singlet, benzene ring H)

5.53 (1h, singlet, 5-position H)

4.45 (1h, singlet, 3-position H)

3.55 (3h, singlet, 6-position OCH₃)

1.60 (3h, singlet, 2-position CH₃)

1.45 (21h, singlet, 2-position CH₃ and benzene ring t-butyl)

1.22 (9H, singlet, pivaloyl)

EXAMPLE 19 Benzhydryl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-6α-metoxypenicillanate

Following the same procedures as described in Example 17, there wasobtained 400 mg. of benzhydryl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-6α-methoxypenicillanatefrom 1.89 g. of benzhydryl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)penicillanate.

Ir spectrum ν_(max) ^(nujol) cm⁻¹ : 3640, 1770, 1750, 1630

Nmr spectrum δ ppm (CDCl₃)

8.42 (1H, singlet, 6-position CH═H).

7.60 (2h, singlet, 6-position benzene ring H)

7.25 (10h, singlet, benzhydrylester benzene ring H)

6.87 (1h, singlet, COOCH φ₂)

3.51 (2h, singlet, benzene ring OH and 5-position H)

4.44 (1h, singlet, 3-position H)

3.46 (3h, singlet, 6-position OCH₃)

1.53 (3h, singlet, 2-position CH₃)

1.38 (21h, singlet, 2-position CH₃ and t-butyl)

EXAMPLE 20 2,2,2-Trichloroethyl7β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-7α-methoxy-3-methyl-2-cephem-4-carboxylate

To a solution of 1.45 g. of 2,2,2-trichloroethyl7β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-3-methyl-2-cephem-4-carboxylatein 50 ml. of benzene was added 2.5 g. of lead dioxide, and the resultingmixture was stirred at room temperature for 25 minutes. Insolubles werefiltered off, and 20 ml. of methanol was added to the filtrate. Then,the mixture was allowed to stand at room temperature for 2 hours. Thereaction mixture was concentrated, and the residue was purified by a drysilica gel column chromatography (3 × 25 cm, eluent; ethylacetate-cyclohexane, 1 : 5) to give 126 mg. of 2,2,2-trichloroethyl7β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-7α-methoxy-3-methyl-2-cephem-4-carboxylate.

Nmr spectrum δ ppm (CDCl₃)

8.46 (1H, singlet, 7-position CH═N)

7.66 (2h, singlet, benzene ring H)

5.91 (1h, broad, 2-position H)

5.59 (1h, broad, benzene ring H)

5.36 (1h, singlet, 6-position H)

4.91 (1h, broad, 4-position H)

4.78 (2h, doublet, CH₂ CCl₃)

3.53 (3H, singlet, 7-position OCH₃)

1.93 (3h, singlet, 3-position CH₃)

1.44 (18h, singlet, t-butyl)

Following the same procedure as described above except for employing thecorresponding benzhydrylester in place of the 2,2,2-trichloroethylester,there was obtained benzhydryl7β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-7α-methoxy-3-methyl-2-cephem-4-carboxylate,yield 21.8%.

Ir spectrum ν_(max) ^(CHCl).sbsp.3 cm⁻¹ : 3650, 1765, 1745, 1690, 1660,1630

Nmr spectrum δ ppm (CDCl₃)

8.42 (1H, singlet, CH═N)

7.60 (2h, singlet, 7-position benzene ring H)

7.24 (10h, singlet, COOCH Ph₂)

6.83 (1H, singlet, COOCH Ph₂)

5.83 (1H, broad, 2-position H)

5.54 (1h, singlet, benzene ring H)

5.26 (1h, singlet, 6-position H)

4.81 (1h, broad, 4-position H)

3.45 (3h, singlet, 7-position OCH₃)

1.73 (3h, singlet, 2-position CH₃)

1.38 (18h, singlet, t-butyl)

EXAMPLE 21 Benzhydryl3-acetoxymethyl-7β-(3,5di-tert.-butyl-4-hydroxybenzylideneamino)-7.alpha.-methoxy-2-cephem-4-carboxylate

Following the same procedures as described in Example 20, benzhydryl3-acetoxymethyl-7β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-7.alpha.-methoxy-2-cephem-4-carboxylatewas obtained from benzhydryl3-acetoxymethyl-7β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-2-cephem-4-carboxylate,yield 24.6%.

Ir spectrum ν_(max) ^(CHCl).sbsp.3 cm⁻¹ : 3650, 1770, 1745, 1635

Nmr spectrum δ ppm (CDCl₃)

8.43 (1H, singlet, CH═N)

7.62 (2h, singlet, 7-position benzene ring H)

7.24 (10h, singlet, COOCH Ph₂)

6.83 (1H, singlet, COOCH Ph₂)

6.26 (1H, broad, 2-position H)

5.51 (1h, singlet, benzene ring OH)

5.17 (1h, singlet, 6-position H)

5.08 (1h, broad, 4-position H)

4.47 (2h, singlet, 3-position --CH₂ O--)

3.39 (3h, singlet, 7-position OCH₃)

1.85 (3h, singlet, OOOCH₃)

1.37 (18h, singlet, t-butyl)

REFERENTIAL EXAMPLE 1

In 5 ml. of dichloroethane was dissolved 200 mg. of the benzhydryl7α-methoxy-7β-(4-hydroxy-3,5-di-tert.-butylbenzylideneamino)-3-acetoxymethyl-3-cephem-4-carboxylateobtained in Example 2 and 100 mg. of thienylacetic chloride was addedthereto. Stirring was effected at room temperature for 2 hours. Thereaction mixture was purified on a thin-layer chromatography (silicagel; 20 × 20 cm, a thickness of 0.2 cm; developing solvent ethylacetate-benzene (1 : 4)), the substance existing in the neighbourhood ofR_(f) 0.45 was extracted with ethyl acetate. The extract wasconcentrated under reduced pressure to give 60 mg. of benzhydryl3-acetoxymethyl-7α-methoxy-7β-(2-thienylacetamido)-3-cephem-4-carboxylate.

Nmr spectrum (CDCl₃) δ ppm:

2.0 (3-position OCOCH₃, singlet),

3.30 and 3.45 (2-position H₂, AB type),

3.48 (7-position OCH₃, singlet), ##STR17## 4.90 and 5.05 (3-position-CH₂OCOCH₃, AB Type) 5.08 (6-position H, singlet),

6.9 - 7.5 (thiophene H, multiplet),

7.05 (COOCH (C₆ H₅)₂, singlet),

7.35 (COOCH (C₆ H₅)₂, singlet)

The benzhydrylester is hydrolyzed with trifluoroacetic acid in amisolein a usual manner to give3-acetoxymethyl-7α-methoxy-7β-(2-thienylacetamido)-3-cephem-4-carboxylicacid.

REFERENTIAL EXAMPLE 2 2,2,2-Trichloroethyl6β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)penicillante

A mixture of 1 g. of 2,2,2-trichloroethyl 6β-aminopenicillanate and 674mg. of 3,5 di-tert.-butyl-4-hydroxybenzaldehyde in 40 ml. of benzene wasrefluxed for 1 hour in a vessel equipped with a water separator. Thereaction mixture was concentrated, and the residue was dissolved in asmall amount of a mixture of ethyl acetate and cyclohexane (1 : 10).Insolubles were filtered off, and the filtrate was purified by a drysilica gel column chromatography (3 × 32 cm, eluent; ethyl acetate -cyclohexane, 1 : 10) to give 1.11 g. of the desired product as a paleyellow syrup.

Nmr spectrum δ ppm (CDCl₃)

8.46 (1H, doublet, J=2, CH=N),

7.56 (2h, singlet, benzene ring H),

5.61 (1h, doublet, J=4, 5-position H),

5.50 (1h, broad, CH),

5.33 (1h, quartet, J=2 and 4, 6-position H),

4.85 and 4.65 (each, 1H, doublet, J=12, CH₂ CCl₃),

4.47 (1H, singlet, 3-position),

1.69 and 1.53 (each, 3H, singlet, 2-position CH₃),

1.39 (18h, singlet, t-butyl)

The pivaloyloxymethylester and the benzhydrylester were obtained in thesame manner as above.

REFERENTIAL EXAMPLE 3 2,2,2-Trichloroethyl7β-(3,5-di-tert.-butyl-4-hydroxybenzylideneamino)-3-methyl-2-cephem-4-carboxylate

A solution of 2.14 g. of 2,2,2-trichloroethyl7β-amino-3-methyl-2-cephem-4-carboxylate and 1.3 g. of3,5-di-tert.-butyl-4-hydroxybenzaldehyde in 60 ml. of benzene wasrefluxed for 1.5 hours in a vessel equipped with a water separator.After evaporation of the solvent, a small amount of cyclohexane wasadded to the residue. Insolubles were filtered off, and the filtrate waspurified by a dry silica gel column chromatography (4.5 × 15 cm, eluent;ethyl acetate-cyclohexane, 1 : 10) to give the desired product.

Yield 1.84 g.

Nmr spectrum δ ppm (CDCl₃)

8.53 (1H, doublet, J=2, CH=N),

7.60 (2h, singlet, benzene ring H),

6.04 (1h, broad, 2-position H),

5.53 (1h, broad, OH),

5.45 (2h, multiplet, 6- and 7-positions H),

4.88 (1h, broad, 4-position H),

4.79 (2h, doublet, CH₂ CCl₃),

1.93 (3H, singlet, 3-position CH₃)

1.44 (18h, singlet, t-butyl)

The benzhydrylester was obtained in the same manner as above.

What is claimed is:
 1. A process for preparing a compound having theformula ##STR18## wherein R⁸ represents a group selected from the groupconsisting of straight or branched lower alkyl, lower alkoxymethyl,benzyloxymethyl, lower alkanoyloxy lower alkyl, benzoyloxymethyl,cyanomethyl, 2,2,2-trichloroethyl, phthalimidomethyl, benzyl,p-methoxybenzyl, p-nitrobenzyl, benzhydryl, phenacyl, p-bromophenacyl,p-methoxyphenacyl, p-nitrophenacyl, and tri lower alkylsilyl, R⁹ to R¹²may be the same or different and each represents hydrogen or a groupselected from the group consisting of straight or branched lower alkyl,lower alkoxy, halogen, cyano, lower alkoxycarbonyl, or R⁹ and R¹⁰together and R¹¹ and R¹² together may be linked to form a ring fusedwith the benzene ring to which they are attached,n is 1 or 2 and Rrepresents a straight or branched alkyl having from 1 to 6 carbon atomswhich comprises contacting a penam compound having the formula ##STR19##wherein R⁸ to R¹² and n have the same meanings as defined above, with ametal oxide in an inert solvent or with a quinone compound substitutedwith an electron attractive group thereby oxidizing said panam compoundto its quinoid form, and contacting the resulting oxidation product witha lower alkanol having the formula R--OH wherein R has the same meaningas defined above, said metal oxide and said quinone compound being onewhich oxidizes phenol to a quinoid form without destruction of the penamnucleus.
 2. A process according to claim 1 wherein said metal oxide islead dioxide and said inert solvent is benzene.
 3. The process accordingto claim 1, wherein said quinone compound isdichlorodicyanobenzoquinone.
 4. The process according to claim 1,wherein the metal oxide is lead dioxide, said solvent is benzene andsaid lower alkanol is methanol.
 5. The process according to claim 1,wherein R⁹ and R¹¹ are each hydrogen, R¹⁰ and R¹² are each tertiarybutyl, and R is methyl.
 6. The process according to claim 5, wherein themetal oxide is lead dioxide and the solvent is benzene.
 7. The processaccording to claim 5, wherein the said quinone compound isdichlorodicyanobenzoquinone.
 8. The process according to claim 1,wherein the penam compound is so contracted at a temperature of up toabout 80° C.
 9. The process according to claim 1, wherein the alkanol isused in an excess of the stoichiometric amount related to the amount ofthe oxidation product.
 10. The process according to claim 1, wherein theresulting oxidation product is so contacted at a temperature of fromabout 40° C. to about 50° C.